I searched the forums but couldn't find an answer to this one, so am hoping someone can help with a strange problem. The short version is that it appears I have gas leaking from the bottom of MAF, but my car hasn't thrown any codes.

I have an 89 Vette with L98 engine. A few days ago, my car didn't want to idle. I could start it but if I let off the gas, it died. After letting it sit for a minutes or two, it fired up fine and didn't have issues additional issues (other than a repeat performance that evening). The next day, after getting home and turning off the engine, I noticed a slight gas smell in the air but really didn't think too much of it.

But yesterday, while I was checking all the fluids, I noticed that gas was (very) slowly dripping from the bottom of the MAF sensor. I felt the bottom and discovered that the bottom section of the MAF wasn't seated well inside the MAF body, so I pushed it back inside as well as I could. I also noticed that the seal was coming apart (may because gas had deteriorated it?). My first thought was the MAF needed to be replaced, but I don't understand how/why gas would be getting to the MAS in the first place.

Any ideas what could be causing this or what I should check?

 

Charcoal Canister may be soaked with gas from a broken check valve. Fumes are sucked in at the bottom of the Throttle Body. Remove the Canister and if there's gas in it, you'll need a new one and the valve which is on the rail near the left front wheel. You may also need a new MAF. I'd get the Canister straightened out (assuming that's it) and see what it does.

Other possibility is broken Fuel Regulator. See if there's fuel in the vacuum hose that connects to the rear of the Plenum. If so, replace the Regulator and then see what it does before replacing the MAF.

 

Get that fixed before you try starting the car. I work at a hospital and you do NOT want to experience the injuries that exploding gasoline fumes cause. Not to mention what it will do to your Corvette.
Make sure you are working in a well ventilated area with no chance of any sparks or open flames.

 

I say it's a ruptured fuel pressure regulator diaphragm. Pull off the vacuum line and check for fuel inside.

Don't wait to fix this. My ruptured FPR diaphragm caused a fire. When I took the plenum off fuel poured out of it.

Mine looked like this after I emptied the fire extinguisher on it (note melted lens on fuel pressure gauge and extinguisher powder EVERYWHERE -- you can see where the vacuum line blew off the FPR and sprayed fuel all over the rear of the engine. The fuel ignited when it hit the catalytic converter.):

 

It's the Fuel Pressure regulator. 100% guaranteed. Cliff, you told me about your incident about 5 weeks ago when mine blew and hydrolocked my engine. First thing Jeebs... loosen your gas cap. That will stop the pressure in your gas tank from pushing gas through the tear in the FPR diaphragm up into your plenum and down into your cylinders and through the front of your air cleaner. Then hit autozone.

If your air cleaner was soaked with gasoline like mine was, pick that up, order the Fuel Pressure Regulator diaphragm, you may need to change your oil after you get this repaired also as the gasoline flows through FPR rip to plenum, down into cylinders (past rings into your oil thinning it), out your MAF (mine was ruined from gasoline and I had to get another). You will also need intake plenum gaskets and will only use three of them. The Felpro ones are cool. The most expensive part is the diaphragm at $70. You rebuild it, not replace it. It's easy.

Get a couple of cans of carb cleaner too as you will find carbon and crap was loosened in your plenum and ran through the throttle body mucking it up.

Also, this past weekend I had to replace the EGR Valve (around $50) which is under the plenum too. You should do that while you have it off.

I'll find my thread and post the link in a few minutes but first, DON'T try and drive it, Loosen the cap and get the parts.

This is cool, I get to return some help to the board after all the help and advice you guys have given me.

http://forums.corvetteforum.com/c4-g...ith-video.html

http://forums.corvetteforum.com/c4-g...ine-dudes.html

 

Sorry it's taken so long to respond, but I had surgery right after my initial post, and my recovery took much longer than expected. StuK and Cliff Harris both thought the fuel pressure regulator may be the problem, and they were correct. Both diaphragms on the regulator were either cracked, or had an outright tear. Replaced the entire fuel pressure regulator and the car fired right up. Thanks again to all who responded!